A decade after crossing the inter-Korean land border with box-loaded documents on North Korea's nuclear program, Amb. Sung Kim is back in talks with North Korea.

The State Department's top Korea expert is meeting with North Korean officials to prepare for an unprecedented summit between Pyongyang and Washington expected to take place in Singapore on June 12, according to the U.S. government.

His team, also involving Allison Hooker, a White House official on Korea, is visiting the North, reportedly focusing on discussing summit agenda items, especially denuclearization.

Meanwhile, other Trump aides, including Joe Hagin, White House deputy chief of staff for operations, are traveling to Singapore for consultations with North Koreans largely on security measures and logistics related to the Singapore summit originally slated for June 12 and later canceled.

Chances are high that it will be held as initially agreed, given the revival of a rather positive tone especially in the wake of the surprise inter-Korean summit on the weekend, the second in a month.

If this week's dual-channel consultations between the North and the U.S. fare well, Secretary of State Mike Pompeo may meet Kim Yong-chol, a senior North Korean Workers' Party official, to put the final touches to pre-summit talks.

Sung Kim's return to talks with North Korea is noteworthy for his expertise on the secretive communist regime.

It indicates the Trump administration's desire for success in dealing with Pyongyang.

Kim, currently ambassador to the Philippines, was a key player in the previous round of brisk nuclear negotiations on the North's nuclear program under the Bush administration.

In May 2008, when he served as director of the State Department's Korea office, he visited the North and crossed the Military Demarcation Line (MDL) at Panmunjom into South Koreas carrying boxes loaded with documents on the North's activity at the Yongbyon nuclear complex for a verification process.

This was the result of the six-way nuclear talks, during which he met several times with Choe Son-hui.